Methods: The Vicon 250 motion analysis system, 3 AMTI force platforms and the EMG recording system will be used to collect data of sit-to-stand (STS) movements. Baseline, pre- and post-training evaluations will be carried out. The duration of the baseline and pre-training evaluations is 2 months. The training period will take about 6 weeks. Each evaluation will take two separate days to accomplish. On the first day, the STS1RM of individual children was determined. On the second day, kinematic and kinetic data of STS movements in natural and loaded (applying load of 50% STS1RM during STS movements) conditions were collected. Data of smoothness, maximal extension moment and around hip and knee joints, onset time of lower extremity muscles will then be calculated. Results of each evaluation will be used for further comparison.